Acquired immune deficiency syndrome (AIDS) is a major health threat throughout the world. HIV is the leading cause of AIDS. To date there are no effective vaccines for AIDS. For these reasons there are great efforts to create vaccines and suitable models for testing the vaccines. One target of therapeutic vaccines is the envelope protein of HIV (gp160). During infection, gp160 is cleaved by host cell proteases to from the gp120 and gp41. Barnett et al. (US2002/0146683) describes numerous HIV Env polypeptides in which at least one of the native B-sheet configurations has been modified. The constructs are taught to be used in vaccine compositions. Vajdy et al. (US2005/0175631) teaches pharmaceutical compositions for the treatment of AIDS in which the compositions have an HIV antigen and a mucosal adjuvant.
To identify promising vaccine candidates, it is important to know which parts of HIV-1 Env are immunogenic and able to induce protective antibodies in the host [Zolla-Pazner S (2004). Nat Rev Immunol 4: 199-210]. X-ray crystallography has revealed important structural Env features and sites of interaction with cellular receptors; it is becoming evident that conserved Env parts are hidden from the immune system [Pantophlet R, Burton D R (2006). Annu Rev Immunol 24: 739-769; Kwong P D, et al. (2000). Structure 8: 1329-1339]. Thus far, however, this important information has not yet been translated into a potent vaccine.